The relationship between the development of delayed hypersensitivity (DTH) and acquired antituberculous and anti-typhoid immunity will be continued using the mouse model. Extracellular protein antigens released by logarithmically growing cultures of BCG, H37Rv and H37Ra and from S. enteritidis are being concentrated, purified and characterized. The antigens from strains of differing immunogenicity will be compared immunochemically with the corresponding tuberculopolysaccharide and lipopolysaccharide antigens. Mice will be immunized by introducing the protein antigen into BCG activated lymph nodes and the development of specific DTH and acquired resistance will be quantitated. The responses to these antigens will be compared with the live vaccine and preparations presented to the host in conventional adjuvanting emulsions. Interactions between the humoral and cellular responses to the purified protein antigens of both actively infected and actively immunized mice will be compared using both the Mycobacterial and Salmonella infection models. The levels of hypersensitivity and acquired cellular resistance will be compared in animals preimmunized in such a way that maximum humoral responses might be expected and then challenged with the living organism. T cell depleted mice will continue to be used in an effort to assess the contribution of B and T cells in the expression of antimicrobial resistance to these organisms.